Presbyopia is an impairment of near vision that results from a gradual loss of lens accommodation usually after the age of 40 to 45 years. It is the most common physiological change occurring in the adult eye and may significantly affect quality of life and productivity when uncorrected (Frick et al., 2015, Ophthalmology 122(8): 1706-1710; Goertz et al., 2014, Acta Ophthalmologica 92(6): 497-500; Patel et al., 2007, Community eye health/International Centre for Eye Health 20(63): 40-41). The main symptom of this condition is a progressive blurring of vision when performing near tasks (reading, sewing, working at a computer etc.). This can occur in the absence of any visual symptoms associated with distance vision. It is estimated that global prevalence of presbyopia will be 1.4 billion individuals by 2020 (Holden et al., 2008, Archives of Ophthalmology 126(12): 1731-1739).
Methods for correcting presbyopia may involve both fixed and variable-focus lens systems (spectacles or contact lenses with monofocal, bifocal or multifocal design), and surgical procedures which modify the optics of the cornea, replace the crystalline lens with different fixed optics, or attempt to at least partially restore active accommodation (Charman, 2014, Ophthalmic & Physiological Optics: the Journal of the College of Optometrists 34(1): 8-29, Charman, 2014, Ophthalmic & Physiological Optics: the Journal of the College of Optometrists 34(4): 397-426; Gil-Cazorla et al., 2016, British Journal of Ophthalmology 100(1): 62-70). However, corrective lens systems may be cumbersome or provide inadequate treatment, while surgical methods can be invasive and are not without risks. For example, a patient may have trouble with night vision after the surgical intervention. Currently, no clinically effective pharmaceutical preparations are available to treat the symptoms of presbyopia.
Accordingly, to avoid the clear disadvantages for patients who are forced to wear corrective lenses or to undergo undesired surgeries with risks, there remains a need for new ways of ameliorating or correcting presbyopia.